In grinding work for flattening surfaces of concrete, stone materials or the like with a power tool such as an electric power tool, an air tool, or an engine tool including a disc grinder or a sander, a diamond wheel is used as the tip tool thereof. The diamond wheel is of wheel type (disc type) in which a plurality of diamond grindstones are fixed on a surface of a cup type substrate whose central portion is formed in a cup shape, and it is used after being mounted on the output shaft (spindle) of the power tool at the axial center of the substrate.
In the grinding work with the power tool like this, since the grinding is carried out while the diamond grindstone is pressed against a material to be ground, vibrations caused by shocks at the grinding are directly transmitted to a worker, and it is difficult to continue the work for a long period of time.
In view of this, for example, in a power tool disclosed in Japanese Registered Utility Model No. 3096194 (Patent Document 1), an elastic member is disposed at a mounting portion for a tip tool so as to absorb the shock occurring at the grinding work, thereby reducing the vibrations transmitted from the tip tool to the worker.